1. Field of the Invention
The present invention relates to an apparatus for the production of a vertical oscillatory lifting movement of a continuous casting ingot mold for metal, especially steel, the apparatus including at least one mechanical drive element which produces adjustable oscillations, which is supported by a foundation, and which moves a continuous casting ingot mold.
A high degree of operating reliability is required of the equipment employed for the oscillation of a continuous casting ingot mold for metal. It should be noted that the metal molds for continuous casting installations have a weight of about 60 tons and are typically located in the adverse and corrosive atmosphere of the pouring area, generally referred to as the "teeming aisle" in the trade. Despite these adverse conditions, high demands are nonetheless placed on the accuracy of the lifting adjustment.
2. Background Information
A mechanical press is described in published European Patent Application No. 073089, which has a drive element coupled to a shaft, the shaft being equipped with a connecting rod connected flexibly with a pushrod which is guided and is flexible in relation to the press table. An almost 90.degree. angle is produced with this drive element and the output lift by the movement of the drive shaft. This document contains no suggestion for an arrangement for the production of a vertical lifting movement of continuous casting ingot molds where the rotation axis of a rotating plate is arranged in the same direction of movement of the ingot mold.
German Patent Application No. 1 4 33 048 shows a lifting device for metal molds consisting of a lifting control unit utilizing a driven disk. In the device disclosed, two-armed levers are located in the flux of force with the mold, and the movement of the shaft of the disk-like drive changes the vertical lift direction of the mold by 90.degree. in relation to the crankshaft axis. Such an arrangement has a multitude of mechanical components which are connected with one other in a sliding manner. One particular disadvantage of this apparatus is, on one hand, the high wear and tear of the elements, and on the other hand, the inaccuracy during the guiding of the molds, due to the multitude of employed elements, reinforced again by the transmission of the two-armed levers which are employed.
A device for the oscillation of a mold in a continuous casting installation is disclosed in Japanese Utility Model No. 44 888/74, wherein eccentric shafts are located below the molds. This arrangement has the disadvantage that important components, which are in danger of wear or erosion, are located directly in the area of the mold. This holds particularly true for a possible lifting height adjustment.
An oscillation drive element is also shown in Austrian Patent No. 333 997, especially for use on molds in continuous casting installations. This oscillation drive element is part of a continuous casting installation, wherein the swivelling driven mold is located on one end of a balancing beam, on the other end whereof there is provided a pivoting connecting rod which is fastened to a transmission. The transmission contains a lifting adjustment gear unit which can be driven by a motor. A change in the oscillation amplitude can be achieved whereby the crankpin axle is relatively changed with the gear unit axle or with the axle of the driving tooth gear, respectively. During the operation of the oscillation drive, the crank shaft circles around the axle of the gear unit and, depending upon the angle of position of the crankpin, the crankpin likewise circles around the axle, whereby variable amplitudes may be generated.
One disadvantage of such an arrangement is that the eccentric cam can only be changed in rather large increments. These increments are achieved with only small reductions to the oscillations of the mold. Additionally, there is the fact that, especially with this type of installation with a balance beam, where there is a relatively large number of elements, especially bearing areas, inaccuracies in the adjustment of the lifting height may occur. One source of error can be found through the change of the levers of the balance beam and the connecting rod. Another source of error can be found in the system relating to the shaft and bearing, especially the change of the inside hole of the bearing through wear and tear.
Getriebeblattern AWF 633 T (an industrial publication whose name translates from the German as "Transmission Pages") discusses the lifting change during movement, and here lift change is known through the reciprocal rotation of a double eccentric (or cam) with the help of a worm gear transmission. [Reference is particularly made to the examples shown in pictures 6 and 7 of this publication.]In the same publication, under picture 1, a change in the eccentricity of one disk during the movement through a "wedge pushing transmission" is shown. In order to perform an adjustment, the wedge-shaped part has to be axially changed with the bearings. Both eccentrics are not suitable for a lift adjustment during operation.
Another mold drive is described in Stahlstrang-Giessanlagen G. Baumann, Verlag Stahl und Eisen mbH, Dusseldorf 1976, particularly in pictures 177 and 178 thereof, which show a lifting and lowering of a lifting table which is connected with a pushrod, as well as two steering mechanisms driven by a motor and bevel gearing which drives a crank disk drive.
One disadvantage of such an apparatus lies in the fact that, between the start and the stop of the lift movement, there is a relatively large number of parts, the accumulated errors of which lead to inaccuracies in the desired lifting movement.
Additional examples of continuous casting molds are disclosed in U.S. Pat. No. 4,807,691 to Schneider, et al., issued Feb. 28, 1989 and entitled "Mold for Continuous Casting of Metal" and in U.S. Pat. No. 4,703,789 to Reichelt, et al., issued Nov. 3, 1987 and entitled "Controlling Mold Oscillations."